Method and/or apparatus for continuous production of 4-plywood

ABSTRACT

Conventional glue applicator rollers and associated doctor rolls including a detachable mechanism which imparts a reciprocal motion to the doctor rolls during the operation of the apparatus. The initial unequal spacing of the doctor rolls from the applicator rollers is maintained during operation with the result that the upper and lower surfaces of a veneer ply receive unequal glue coatings. Reciprocating the doctor rolls reverses the surface to which the greater amount of adhesive is applied as veneer plies pass through the applicator rollers, thus facilitating the continuous fabrication of 4-ply laminates with a strong balanced glue line.

United States Patent [1 1 Hopping n1] 3,710,760 1 Jan. 16, 1973 [54]METHOD AND/OR APPARATUS FOR CONTINUOUS PRODUCTION OF 4- PLYWOOD [75]Inventor: William J. Hopping, Pocomoke City, Md.

[73] Assignee: Champion International Corporation 22' Filed: Jan. 25,1971 [21] Appl. No.: 109,469

Related U.S. Application Data [62] Division of Ser. No. 769,216, Oct.21, 1968, abandoned.

[52] U.S. Cl ..118/227, 118/262 [51] ..B05c U112 [58] Field of Search..118/224, 227, 228, 262

[56] References Cited UNITED STATES PATENTS 2,775,953 1/1957 McFall..118/262 X 3,279,426 10/1966 Atkins et al. ..118/227 1,202,337 10/1916Whitney et al.

1,661,174 3/1928 Francis 2,359,904 10/ l 944 Fluckinger ..l 18/227Primary'ExaminerJohn P. Mclntosh A tt0rneyl-leilman & Heilman [57]ABSTRACT Conventional glue applicator rollers and associated doctorrolls including a detachable mechanism which imparts a reciprocal motionto the doctor rolls during the operation of the apparatus. The initialunequal spacing of the doctor rolls from the applicator rollers ismaintained during operation with the result that the upper and lowersurfaces of a veneer ply receive unequal glue coatings. Reciprocatingthe doctor rolls reverses the surface to which the greater amount ofadhesive is applied as veneer plies pass through the applicator rollers,thus facilitating the continuous fabrication of 4-ply laminates'with astrong balanced glue line.

8 Claims, 3 Drawing Figures PATENIEDJAHIBIHYS: 3.710.760

INVENTOR WILLIAM J. HOPP ATTO R NE Y.

VIII/114m? METHOD AND/R APPARATUS FOR CONTINUOUS PRODUCTION OF 4-PLYWOODFIELD OF THE INVENTION This application is a division of Ser. No.769,216 filed Oct. 21, 1968.now abandoned.

This invention relates to plywood articles and more specifically to anapparatus for forming 4-ply laminates.

Plywood is a well-known material which has found widespread use in manyapplications and industries, particularly the building constructionindustry. This material is essentially a laminate consisting of an oddnumber of veneers or plies glued over each other, usually with adjacentplies placed so that their grain direction is at 90. The laminated pliesare conventionally joined in continuous production by a mechanism havingglue applicators in the form of rollers which apply glue to the surfacesof the plies as they pass. Several plies are joined to the adhesivelycoated plies which form the central or core section and the plywoodarticle isformed upon hardening of the glue.

There are several problems associated with the a'pparatus and processesnormally employed in the industry for the continuous production ofplywood. For example, only 3-ply or S-ply laminates can be efficientlyproduced on a continuous basis due to a variety of factors which must beconsidered. These may be explained as follows. Since adjacent plies mustbe glued together, one or more of the contiguous surfaces must have glueapplied thereto. However, for the process to be efficient, it ispreferable that only one of the surfaces have a glue coating providedthat it is sufficient in quantity to impart the properstrength to thejoint. But greater efficiency is achieved if both surfaces of a passingply are given a glue coating by the applicator rolls simultaneously.Moreover, further processing difficulty is encountered when therequirement of a balanced glue line between all ply joints in a plywoodarticle is considered. Such a balanced glue line is important since alljoints must be of v comparable strength or the final product will haveweak areas. Therefore, in order to satisfy all of these requirements,only an odd number of plies can be laminated by the conventionaltechnique. Thus, in a 3-ply article the center piy or core has glueapplied to both surfaces and the outer plies are not given a gluecoating. ln a 5-ply laminate, the alternate inner plies are coated onboth surfaces, while the remaining three plies are not provided with anadhesive. Obviously, a 4-ply laminate cannot be efficiently produced bythis process since adjacent plies would each be coated and when they arejoined, an excess quantity of glue would form in the joint therebyadversely affecting the quality of the product, and the cost thereof.

It is apparent, therefore, that there is a great need in the plywoodmanufacturing industry for an apparatus and a process which will enablea plywood article having an even number of plies to be efficientlyproduced. It is the primary object of this invention to provide such anapparatus.

SUMMARY OF THE INVENTION Broadly, the apparatus of the inventioncomprises applicator means preferably in the form of a pair of spacedrollers, retarding means positioned proximate and adjacent theapplicator means for retarding the flow of adhesive material from theapplicator rollers, and means for moving the retarding means toward oraway from the applicator rollers to increase or decrease the flow ofadhesive. in the operation of the apparatus, an adhesive material suchas glue is continuously applied to the applicator rollers and veneerplies are passed between the rollers. As they pass, the plies are coatedwith the adhesive on the upper and lower surfaces. However, thevariation in pressure on the applicator rollers due to the motion of theretarding means enables the quantity of adhesive flowing from therollers to be controlled during the process. By altering the pressurecycle on each applicator separately, an unequal quantity of adhesive isapplied to the upper and lower surfaces of a passing ply. Furthermore,by continuously reciprocating the retarding means out of phase with eachother, the greater quantity of adhesive is applied to opposite surfacesof each succeeding ply passing through the applicator rolls. Thus, ifthe first ply is coated with twice as much adhesive on the upper surfaceas on the lower surface, the next ply will be coated with twice as muchadhesive on the lower surface due to the out of phase reciprocatingmotion of the retarding means. The two surfaces with less adhesive canbereadily joined without an excess of adhesive occurring in the joint,and when two uncoated outer plies are added, a 4-ply laminate iseffectively produced on a continuous basis.

More specifically, the apparatus of the invention comprises in additionto the spaced applicator rollers, a pair of cylindrical rollstangentially spaced from the applicator rollers to act as retardingmeans, an inclined rack with at least one pinion movably connectedthereto, gearing means secured between the pinion and the retardingrolls, an air cylinder joined to the rack, and means for activating theair cylinder. Upon activation, the air cylinder imparts motion to therack and pinion and thus to the retarding rolls through the gears. Anincrease or decrease in spacing between retarding rolls and applicatorrollers results from this motion and dispersal of the adhesive materialto the passing plies is controlled as hereinbefore indicated. Means fordisconnecting the rack, pinion and associated equipment are alsoincludedto thereby restore the apparatus to conventional operation, if desired.

The apparatus of the invention enables 4-ply laminates or multiplesthereof 'to be continuously produced thereby satisfying a long standingindustry wide problem. The continuous production is automaticallyeffected by varying the thickness of the glue coating on each core plyand as above-explained, by reversing the surface to which the greateramount of glue is applied. In this manner, any two core plies can bestacked immediately without the necessity of flipping" one or the otherto obtain the proper mating surfaces. The outer surfaces of the stackedlaminates have the proper quantity of adhesive to bind uncoated plies tocomplete the plywood article. The plywood article so produced ischaracterized by having the same quantity of adhesive at the centerjoint as at the outer joints. This is accomplished by joining two halfcoated surfaces in the center and full coated surfaces at the outerjoints.

DESCRIPTION OF THE DRAWINGS The invention will be more readilyunderstood by referring to the drawing, wherein:

FIG. 1 is a front elevational view of the apparatus of the invention;

FIG. 2 is a side elevational view of the apparatus shown in FIG. 1; and

FIG. 3 is a pictorial view, partly in section, of a 4-ply plywoodarticle.

Referring to the drawing, there is shown in FIG. 1 an apparatus which iscapable of mass producing 4-ply laminates. The apparatus 10 comprisesapplicator rollers 12, 14 which rotate in the directions indicated bythe arrows. A veneer ply 16 is passed between rollers 12, 14 such thatits surfaces are contacted by the rollers as they pass therebetween. Anadhesive material such as glue is continuously supplied to the rollerssuch as by passing roller 14 through glue bath 18 and roller 12 throughglue bath 20. Retarding means in the form of doctor rolls 22, 24 arepositioned proximate and adjacent applicator rollers 12, 14,respectively, and form gaps therewith such as at 11,- 13. The size ofthe gaps is inversely related to the quantity of adhesive material whichflows from the applicator rollerstothe veneer ply. The size of each gapis regulated and varied by means comprising a rack 26, pinions 28, 30and worm gears 32, 34. A shaft 36 is connected to rack 26 through pin 38and directly to air cylinder 40. A valve 42 controls the operation ofthe cylinder 40 and is manually operated by foot pedal 44. Rack 26 ispartially supported by cam follower 48 during its movement. i

In the operation of the apparatus, the doctor rolls 22, 24 are initiallyadjusted such that one is closer to the applicator roller than theother. As shown clearly in FIG. I, doctor roll 22 is closer to roller 12than doctor roll 24 isto roller 14. Therefore, as veneer ply 16 passesbetween the rollers, less adhesive is applied to the upper surface ofthe veneer due to the small gap 11 between doctor roll 22 and applicator12. Both surfaces of the veneer ply are coated with an adhesive, but

because of the variation in gap size, the upper surface is provided witha coating about one-half the thickness of the lower surface. As the ply16 passes through the applicator rollers, another similar ply (notshown) is fed to the rollers. Just prior thereto, an operator pressesfoot pedal 44 which activates valve 42 to pass air through air tube 46and thereby operate air cylinder 40. The shaft 36 which is essentiallyan extension of the piston within the air cylinder, moves toward the aircylinder and causes rack 26 to also move in the same direction. As aresult, pinions 28, 30 are rotated by the movement of the rack and themotion is translated through the worm gears 32, 34 to the doctor rolls22, 24. As shown, the pinions rotate in opposite directions and thus themotion of the doctor rolls in a horizontal plane (as shown by thearrows) is such as to withdraw the upper doctor roll 22 from applicatorroller 12 and to extend lower doctor roll 24 toward applicator roller14. As a result, gap 11 is enlarged and gap 13 is reduced. Thus,the nextply through the rollers receives a thicker coating on the upper surface.Thisply is automatically placed on top of the previous ply,-the two thinor half coated surfaces being joined without flipping either ply. Twouncoated plies are then placed contiguously with the joined plies and a4-ply laminate is readily formed. While the laminate is being formed,other veneer plies are passed through the coating apparatus so thatcontinuous production of 4-ply plywood can be effected. In order toreverse the surface to which the greater amount of adhesive is applied,foot pedal 44 is pressed each time a ply is about to enter theapplicator rollers. By this action, air cylinder 40 alternately receivesand releases air through air tube 46 and valve 42. Shaft 36 and rack 26consequently oscillate thereby imparting a reciprocal motion to thedoctor rolls. Because of the arrangement of the rack and pinions, thedoctor rolls are caused to reciprocate out of phase with each other andin this manner, unequal adhesive coatings are continuously supplied tothe surfaces of passing plies.

The gaps 11, 13 are set initially such that one approximately twice thesize of the other. This relation is maintained throughout the operationof the apparatus by proper design of the rack, pinion and air cylinderstroke. By employing pinions of the same size, for example, doctor rolls22, 24 are caused to travel the same distance toward or away from theapplicator rolls as the rack travels longitudinally. By proper selectionof the air cylinder, that is, of the length of the piston strokes, therack moves a distance sufficient to maintain the initial gap size eachtime the air cylinder is actuated. Therefore, each passing ply alwaysreceives twice as much adhesive on one surface as on the other. Ofcourse, adjustments can be made to vary the ratio as required.

It is to be noted that pin 38 can easily be removed to disconnect theshaft 36 and air cylinder 40 from rack 26. The rack may then be removedentirely from the apparatus and doctor rolls 22, 24 reset to formequally spaced gaps. The apparatus is then capable of continuouslyproducing 3-ply or S-ply laminates-in a conventional manner. Thus by asimple attachment and adjustment, a conventional glue coating machine iscon-' verted to a 4-ply producing mechanism.

FIG. 3 illustrates a 4-ply plywood laminate formed by the process andapparatus of the invention. As there shown, veneer plies 50, 52 areprovided with glue coatings while the outer plies 54, 56 have no gluethereon prior to forming the plywood article. Veneer ply 52 has anadhesive coating 58 on the upper surface which is about twice as thickas coating 60 on the lower surface while veneer ply 50 has a thincoating 62 on its upper surface and twice as much coating 64 on theouter plies may also be used. Any other combination of plies, all plieshaving the same or different thicknesses,

may also be used.

Initial individual adjustments of doctor rolls 22 and 24 for a half or afull coat is accomplished by reference guide lines on pinions 28 and 30before the rack 26 is Y positioned to engage the pinions. Obviously anyconventional means, such as-a key or turn wheel, can be used to adjustthese pinions for either a special 4-ply, or regular 3, 5 or 7-plyconstruction.

A simultaneous relative adjustment can be made by sliding rod 36 furtherinto, or not as far into, the partially hollowed out rod 26 beforetightening the screw 38. Alternatively, rack 26 could be extendedthrough reciprocating air cylinder 40 and fastened therein by adetachable pin or bolt 26 at the lower end thereof. Hence, for a regular3-ply operation, i.e., a single core ply having equal thicknesses ofglue on each side of the core, the pin 26 is pulled out, the rack 26moved away and out of engagement with the pinions, and the doctor rollsadjusted for equal quantities of coatings.

From the foregoing, it will be appreciated that the process andapparatus of the invention satisfy an industry wide need for a means andmethod of continuously producing 4-ply plywood articles of excellentquality and balanced strength. Many modifications of the apparatusdisclosed are intended to be within the purview of this invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. An apparatus for providing an adhesive coating of jacent to saidapplicator means for forming first and second gaps with said applicatormeans, said adhesive material being caused to pass through said gapsbefore being applied to said wood ply;

c. A first control means for adjusting the size of the gap between thefirst retarding means and the first applicator;

d. a second control means for adjusting the size of the gap between thesecond retarding means and the second applicator;

e. Means for simultaneously moving said first and second control meansto increase the size of either gap while decreasing the size of theother gap.

2. An apparatus according to claim 1 wherein said first and secondapplicators are cylindrical rolls.

3. An apparatus according to claim 1 wherein said first and secondretarding means are cylindrical rolls.

4. An apparatus according to claim 1 wherein said means forsimultaneously moving said first and second control means comprises agear means terminated in a imparts a continuous out of phase reciprocalmotion to said retarding means.

8. An apparatus according to claim 4 wherein said rack is coupled to anair cylinder piston, and valve means coupled to the cylinder foractuating the cylinder piston.

I UNTKED STATES PATENT OFWCE .QEEHFECAESE @F RREHN 39710 760 Datedfianuary 1 1973' Patent No.

William J. Ho ping Inventor(s) It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Tee title of the invention should read Method end/or Apparatus forContinuous lrouetion of i-Plv Plywood Signed and sealed this 29th day ofMay 1973.

EDWARD M.FLETCHER ,JR. I

Commissioner of Patents Attesting Officer FORM 304050 (10'69) USCOMM-DC60376-P69 [1.5. GOVERNMENT FRINTIING OFFICE I 969 Q356"334

1. An apparatus for providing an adhesive coating of varying thicknessesto wood plies, comprising; a. a first and second applicator means havinga space therebetween for passing wood plies therethrough, saidapplicator means having an adhesive material in contact therewith. b. afirst and second retarding means positioned adjacent to said applicatormeans for forming first and second gaps with said applicator means, saidadhesive material being caused to pass through said gaps before beingapplied to said wood ply; c. A first control means for adjusting thesize of the gap between the first retarding means and the firstapplicator; d. a second control means for adjusting the size of the gapbetween the second retarding means and the second applicator; e. Meansfor simultaneously moving said first and second control means toincrease the size of either gap while decreasing the size of the othergap.
 2. An apparatus according to claim 1 wherein said first and secondapplicators are cylindrical rolls.
 3. An apparatus according to claim 1wherein said first and second retarding means are cylindrical rolls. 4.An apparatus according to claim 1 wherein said means for simultaneouslymoving said first and second control means comprises a gear meansterminated in a pinion gear in mesh with a rack.
 5. An apparatusaccording to claim 4 wherein said rack is longitudinally adjustable forsimultaneous control of each of said retarding means.
 6. An apparatusaccording to claim 4 wherein said rack is adjustable over a distancewhich varies the gap size ratios from two-to-one to one-to-two.
 7. Anapparatus according to claim 4 wherein a relative movement between saidrack and the gear means imparts a continuous out of phase reciprocalmotion to said retarding means.
 8. An apparatus according to claim 4wherein said rack is coupled to an air cylinder piston, and valve meanscoupled to the cylinder for actuating the cylinder piston.